DISCUSSION OF SOME DESIGN PROBLEMS ASSOCIATED WITH ARTIFICIAL FEEL SYSTEMS OF AIRPLANES WITH IRREVERSIBLE POWERED FLIGHT CONTROLS 600260

A basic study was conducted on the longitudinal stick free static and dynamic stability for airplanes with irreversible power control. Methods of improving the airplane flying and handling qualities are presented. With regard to the stick free static stability, trim reversal was apparently eliminated by means of a Mach compensation device which improved the characteristics of stick force speed stability. Stick forces per airplane normal acceleration in steady-state maneuvering flight were tailored to meet the requirements of the military specification by incorporating a Q-bellows bleed air subsystem into the artificial feel system. In the stick free dynamic analysis, residual oscillations of airplane normal acceleration following a step stick force input and control forces in sudden pull-ups have been studied for various feel systems. The system exhibiting the most satisfactory performance was the one which comprised a Q-bellows with Mach and dynamic pressure compensation devices, very light centering springs, low stick friction and no bob weight.